Hydraulic classifier



April 1930. A. w. FAHRENWALD 1,752,791

HYDRAULIC CLASS IFIER Filed Oct. 12, 1925 2 Sheets-Sheet l zzmm m E um 10 O 5 O Q n vzmbok/ fiMw W @hm/m/d April 1930. A. w. FAHRENWALD 1,752,791

HYDRAULIC CLASS IFIER Filed Oct. 12, 1925 2 Sheets-Sheet 2 I y% I N N a 92 N /7//%0/ fM/mm/d (I '5 my I Patented Apr. 1, 1930 vwarren STATES "PATENT OFFICE ARTHUR WILLIAM FAHRENWALD, OF MOSCOW, IDAHO, ASSIGNOR TO THE DORR COMPANY, OF NEW YORK; N. Y., A CORPORATION OF"DELAWARE HYDRAULIC CLASSIFIER Application filed October 12, 1925. Serial No. 623109. v

This invention relates to improvements in hydraulic classifiers of the hindered settling automatic control type, and the object of the invention is the provision ofan apparatus with means of controlling the depth of the hindered settling beds of ore particles in water suspension in the classifier pockets.

Another object is the provision of a novel form of communication between the hydrauhe pressure chamber and the classifying pocket, to produce uniform distribution of rising currents of water in the classifying pocket.

A still further object resides in the provision of a means of controlling the density of the ore pulp in the settling chamber.

Other objects and advantages reside in certain novel features of the construction, arrangement and combination of parts, which will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to the accompanying drawings forming a part of this specification, and in which Figure 1 is a view in vertical section of one embodiment of the invention,

Figure 2 is a View in elevation of the automatic discharge side of the apparatus embodying my invention, portions being cut away to better reveal its details,

Figure 3 is aview in front elevation, partly in section, of the automatic control mechanism, and

Figure 4 is a view in side elevation of the automatic control mechanism,

Figure 5 is a view of a horizontal section on line A-A of Figure 2 showing the form of communication between the hydraulic pressure chamber and the classifying pocket.

Hydraulic classifiers of the hindered settling type employing automatic means for controlling the operation of the classifier may make one or more classified products depending upon requirements in the treatment of the ore. When more than one classified product is desired hydraulic classifiers of this type embody in the one machine the proper number of classifying pockets to give the required number of classified products. In the case of a multiple pocket classifier one settling classifying pocket is provided.

The practical success and metallurgical efficiency of this type of classifier is entirely dependent upon (1) the maintenance of a constant density in the settling chamber 1 of the classifier (2) the uniformity of the uprising currents 1n the classifying pockets 5 and (3) the maintenance at all times, in the various classifying pockets, at constant depth, of a crowded elbowing bed of ore particles in water suspension.

Referring particularly to Figures 1 and 2, constant density in the settling chamber-of the classifier is efiected by the employment of an auxiliary overflow pipe 9, having its lower end extending into the settling chamber 1 to a level just above the final pocket 5 of the classifier, and its upper end communicating with the overflow compartment 4 through the overflow Weir 3 at a suitable distance below the top edge of the weir 3. The pipe 9 has forits purpose the removal from the settling chamber 1 of the sand portion of the ore fed to the classifier that is too light to settle in the ore-water teeter beds in the classifier pockets and that is too heavy to overflow the weir 3. Without this provision the density of this portion of the pulp in the classifier increases and causes a premature functioning of the automatic control mechanism to be hereinafter described. This premature operation results in a disappearance of the ore-water teeter beds within the classifier pockets and in poor classification.

Uniform distribution of uprising water in the classifying pockets 5 is effected by the employment of slotted openings 10 shown in Figure 5, between the hydraulic pressure chamber 8 and the classifying pockets 5. The slots 10 are parallel with each other and extend the entire width or length of the classifier pockets. The width and distance apart of said slots 10 depend upon the nature of the material to be treated.

The distributing action of the slotted type of communication 'from hydraulic pressure chambers to classifying pockets is due to the fact that the slotted type of opening has the greatest continuity of opening of any form of opening. It is due to this high continu ty of opening and the excavating power of flowing water that the formation of dead beds in the classifying pockets is prevented. 1

The slotted form of communication between the hydraulic pressure chambers and classifying pockets also "prevents the passage of oversize ore particles and foreign materials from the classifying pocket into the hydraulic pressure chamber. It does this -more effectively than any other form of opening for the reason that the slotted opening has the greatest maximum dimension and the least minimum dimension for a given total volume of opening of any design of opening. Ore particles approach the spherical form and it is the width of the slot that determines the size of a sphere that may pass through a slottedopening.

The automatic discharge control mechanism shown embodied in the classifier in Figures 1 and 2 and in detail in Figures 3 and 4 has for its express purpose the control of the depths of the ore-water teeter-beds in the classifier pockets and is caused to function by direct pressure of the material within the classifier pockets as will be hereinafter pointed out.

The automatic discharge control, with one of which each pocket is provided, indicated generally by the numeral 11 consists of a flexible diaphragm 12 (Figs. 3 and 4), occupying a portion 13 of one side 14 of each classifier pocket and clamped thereto by a frame 15. The weight of the ore pulp within the classifier acting on the flexible diaphragm 12, which may be considered as a point force acting horizontally on the diaphragm at its center, is supported byan exactly equal and opposite force through the employment of a lever 16, at an acute angle 17'with the wall 14 and pivoted at the apex 18 of said angle. The pivot of the lever 16 is located on the frame 15 just above the diaphragm 12. One arm 16 of the lever 16 hangs approximately perpendicularly below the pivot 18 and includes an offset 19 on which is mounted a disc 20 aligned with the center of the diaphragm 12. Said disc stands in a plane parallel with the diaphragm 12 and is adapted to receive the force exerted on the opposite side of the diaphragm 12 by the ore pulp within the classifier pocket. At the end of the lever arm 16 is the discharge control valve 21 engaginga seat 22 located in the frame 15 6 just below the diaphragm 12. Seat 22 is a hollow bushing through which the classified ore is adapted to pass.

To the other sloping arm 16 of the lever 16 and at a suitable horizontal distance from the pivot 18 is threadedly attached a weight 23. The force of the weight 23 times its horizontal lever arm 16 should at all times be equal and opposite to the force of the pulp times its lever arm 16 The mathematical expression of this static system of forces is F S =F' S where F is the force of the pulp acting on the diaphragm 12, S, the moment arm of this force, F the force of the body 23 and S the moment arm of this force. When the condition within the classifier pockets is correct with respect to depth of ore-water teeter-bed, F S will have a definite value. The value of F S should be adjusted to exactly equal this value by increasing or decreasing the value of S by moving the weight 23 in the proper direction. With the proper conditions within the classifier pockets as observed through a window 24 located in the side of each classifier pocket, the system of forces should be in static balance with the valve 21 pressing lightly against its seat 22. It is evident that any change in the value of the force of the pulp F acting on the diaphragm 12, since the system of forces always remains in static balance, must result in a change in the value of S "and moreover changes in the value of S are accompanied by changes in the position of the lever arm 16 and 16 Thus the valve21 is caused to move from the position of complete closure of the spigot 22 to a completely open osition. Under conditions of uniform fee the valve is never. fully closed or fully opened and the discharge of classified products from the classifier pockets is steady and continuous.

In operation the ground ore along with some water is admitted to the feed compart 2, the coarsest and heaviest particles of the feed, in their hindered settling ratio, settling into the first pocket of the group of classifying pockets 5. Due to the uprising current of water in the classifying pocket the coarse and heavy particles teeter and elbow about each other in a closely crowded condition. The depth of the teetering bed, as observed through the window in the classifying pocket, increases as the feed continues to flow into the classifier. When the teeter bed is seen to occupy something over half the de th of the classifyin matic disc arge should be made, by a proper shifting of the body 23 on the lever arm 16 of the discharge mechanism, so that classified productswill be discharged from the classifying pocket as fast as they accumulate.

It is to be noted that the automatic discharge mechanism is caused to function by a change in depth of the teeter bed within the classifier pockets and not by change in density.

pocket, adjustment 0 the autoy In the type of classifier herein specified there are three zones of action. In the settling chamber 1 is the zone of settling and the density of the pulp in this zone should not change and should be as low as possible. The upper portion of the classifying pockets 5 is the zone of classification and the density of the pulp in this zone remains constant. The lower and greater portion of the classifying pocket 5 is thezon e of accumulation of uniform product and the density of this zone remains constant. It is the change in the depth of the zone of accumulation that causes a change in the force F acting on the diaphragm of the discharge mechanism and that causes itsautomatic operation.

Only one embodiment of my invention is herein specified. One of the objects of the invention is to provide a hindered settling classifier automatic discharge controlled by the direct pressure of the ore-water pulp. It is particularly to be distinguished from the types of automatic discharge heretofore used in this type of classifier, controlled by a column of clear water balanced against a column of the ore-water pulp. The action is a direct one and may be utilized in ways other than the one herein specified; but such variations in mechanical application of the principle of direct pressure fall within the spirit of my invention.

Having described my invention and the principle of its 0 eration, I claim I 1. Apparatus or treating solids suspended in liquid including a container having a solids discharge outlet, a yieldable diaphragm forming a portion of a wall of the container below the normal liquid level, and means operatively connected to the diaphragm for controlling the discharge of solids through said outlet.

2. A hydraulic classifier comprising a compartment having a solids discharge outlet in the lower partthereof, means for producing an upward flow of liquid in the compartment, a diaphragm mounted in a wall of the compartment and movable outwardly by fluid pressure therein, valve means operatively engaging the diaphragm for regulating the discharge of solids through said outlet, and means for varying the amplitude of movement of the diaphragm under predetermined changes in fluid pressure thereon.

3. A hydraulic classifier comprising a compartment having a solids discharge outlet in the lower part thereof, means for producing an upward flow of liquid in the compartment, a diaphragm mounted in a wall of the compartment and movable outwardly by fluid pressure thereon, means for yieldably pressing the diaphragm inwardly against the fluid pressure, and means controlled by the movement of the diaphragm for regulating the discharge of solids through the outlet.

4. A hydraulic classifier comprising a compartment having a solids discharge outlet in the lower part thereof, means for producing an upward flow of liquid in the compartment, a diaphragm mounted in a wall of the compartment and movable outwardly by fluid pressure thereon, valve means for regulating the discharge of solids from said outlet, an. arm engaging the diaphragm and adapted to actuate the valve means by movement "imparted by the diaphragm, and adjustable means for yieldably pressing the diaphragm inwardly against the fluid pressure.

5. A hydraulic classifier comprising a compartmenthaving a solids discharge outlet in the lower part thereof, means for producing an upward flow of liquid in the compartment, a diaphragm mounted in a wall of the compartment and movable outwardly by fluid pressure therein, an arm movable toward and away from the outlet, valve means on the arm engaging the outlet to regulate the discharge of solids therefrom, and an operative connection between the arm and the diaphragm for imparting to the arm movements relative to the outlet corresponding to outward and inward movements of the diaphragm under variations in the fluid pressure thereom 6. A hydraulic classifier comprising a compartment having a solids discharge outlet in the lower part thereof, means for producing an upward flowof liquid in the compartment, a diaphragm mounted in a wall of the compartment and movable outwardly by fluid pressure thereon, valve means for regulating the discharge of solids from the outlet, a pivotally supported rod engaging the diaphragm and the valve means on the same side of the pivot point for operation of the valve means in conformity with movements of the diaphragm caused by variations in fluid pressure thereon, and means for yield ably pressing the diaphragm inwardly.

7. A hydraulic classifier comprising a compartment having a solids discharge outlet in the lower part thereof, means for producing an upward flow of liquid in the compartment, adiaphragm mounted in a wall of the compartment and movable outwardly by fluid pressure thereon, valve means for regulating the discharge of solids from the outlet, a pivotally supported rod engaging the diaphragm and the valve means on the same side of the pivot point for operation of the valve means in conformity with movements of the diaphragm caused by variations in fluid pressure thereon, and an adjustable counter-weight connected to the arm positioned to oppose outward movement of the diaphragm.

8. A hydraulic classifier including a sedimentation compartment, a plurality of classification compartments in series connecting with the bottom of the sedimentationcompartment, means for producing an upward current of liquid'in each classification compartment, overflow discharge means in the sedimentation compartment at an end of the series located substantially above the upper level of the classification compartment, and means for discharging from the sedimentation compartment solids incapable of either settling in'the classification compartment or of overflowing, said means comprising a separateoverflow discharge passage having its inlet adjacent said overflow means and the upperlevel of the classification compartments, and its outlet below the level of said overflow means.

9. A hydraulic classifier including a sedimentation channel adapted to receive feed at one end, a series of classification compartments connecting with the bottom of the channel, means for producing an upward flow of liquid in each classification compartment, an overflow weir across the sedimentation channel beyond said series at the opposite end and an auxiliary overflow discharge comprising an upwardly extending passage open at its lower end in the channel adjacent the weir and the upper level of the classification compartments, the other end of the passage extending through the weir and discharging beyond same.

10. A hydraulic classifier comprising a classification compartment having uniform horizontal section throughout substantially its entire height, means for producing an upward current of liquid in said compartment, comprising a bottom for said compartment having openings therein for the introduction of liquid throughout the entire area of the bottom, said openings comprising a'plurality of narrow slots, and means for forcing liquid upwardly through the slotsv at a velocity greater than the settling rate of solids accumulating in the compartment; and means for discharging the solids from the compartment.

11. A hydraulic classifier comprising a classification chamber, a compartment for hydraulic water located beneath the chamber, means for introducing water to the compartment at a pressure adapted to produce an upward flow into the chamber at a rate sufficient to prevent the passage of a substantial quantity of solids into the compartment, and

a bleeder outlet connected to the bottom of I the compartment adapted to discharge visibly a minute quantity of water to indicate the absence of an accumulation of solids in the compartment.

12. Apparatus for treating solids suspended in liquid comprising a container having a solids discharge outlet at one side thereof, means for producing in said compartment a uniform continuous upward flow adequate to maintain a hindered settling condition therein, a valve for regulating the discharge through said outlet, control means located below the normal liquid level in the container and movable in accordance with vari ations in the horizontal fluid pressure exerted by a bed of hindered settling solids in the container, and actuating connections between said control means and the valve, the discharge opening being spaced from said control means.

13.' Apparatus for treating solids, suspended in liquid comprising a container having a solids discharge outlet, in an immovable portion of the side wall, means for producing in said compartment a uniform continuous upward flow adequate to maintain a hindered settling condition therein, a valve for regulating the discharge through said outlet, yieldable control means in a wall of the container below the normal liquid level in the container and movable in accordance with variations in the horizontal fluid pressure exerted by a bed of hindered settling solids in the container, and actuating connections between said control means and the valve, the discharge opening being spaced from said control means.

A. W. FAHRENWALD.

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